As the computer technology continuously progresses, the computer-based multimedia system, constructed with a computer and multimedia devices, is widely used in various occasions, such as offices, households, and business locations. However, the design of the conventional computer-based multimedia systems is basically linking an audiovisual player device to a computer system through a computer interface. With this type of design, the user usually needs to boot the computer system in order to activate and operate the audiovisual player. In other words, the user must wait until the computer system completes the BIOS program initialization, POST program, peripheral detection and driving, operating system activation, system configuration, and so on, before the user can execute the audiovisual program to play the audiovisual data.
In addition, when the computer completes the booting process, all the connected peripherals are activated and in a ready-to-play state, which consumes a considerable amount of power. To save the power consumption and prolong the life span of the computer system, most operating systems of personal computers (PCs), such as Windows XP, Windows 2000, and Windows Me, integrated the power management function of the advanced configuration and power interface (ACPI). Therefore, the power management operation can be performed through the ACPI interface.
The ACPI interface can manage the power consumption of the peripherals. The ACPI interface specifies various power management states, including active, hibernation, standby, and shutdown. Based on the user's setting, the computer system can enter the standby or hibernation state. The standby state is a low-power state, and the hibernation state reduces further power consumption.
In a typical ACPI structure, the power states are defined as:
S0: normal power supply state;
S1: first stage standby state, in which the power to central processing unit, memory, and fan stays on while the power to display and hard disk is off;
S2: second stage standby state, in which the power to central processing unit, cache, monitor, and hard disk is off;
S3: third stage standby state, in which only minimum power stays supplied to RAM;
S4: hibernation state, in which power to all the devices and elements is off, with the operating system storing all the data and execution states before terminating the power supply to the devices and elements; and
S5: shutdown state, in which all the power supply is turned off.
Based on the user's setting, the computer system can enter the standby or hibernation state. The standby state is a low-power state, and the hibernation state reduces further power consumption.